Re: [PATCH V6 01/15] mmc: host: Add facility to support re-tuning

Ulf Hansson
2015-05-04T13:14:23Z

On 20 April 2015 at 14:09, Adrian Hunter <adrian.hunter@intel.com> wrote:
> Currently, there is core support for tuning during
> initialization. There can also be a need to re-tune
> periodically (e.g. sdhci) or to re-tune after the
> host controller is powered off (e.g. after PM
> runtime suspend / resume) or to re-tune in response
> to CRC errors.
>
> The main requirements for re-tuning are:
> - ability to enable / disable re-tuning
> - ability to flag that re-tuning is needed
> - ability to re-tune before any request
> - ability to hold off re-tuning if the card is busy
> - ability to hold off re-tuning if re-tuning is in
> progress
> - ability to run a re-tuning timer
>
> To support those requirements 7 members are added to struct
> mmc_host:
>
> unsigned int can_retune:1; /* re-tuning can be used */
> unsigned int doing_retune:1; /* re-tuning in progress */
> unsigned int retune_now:1; /* do re-tuning at next req */
> int need_retune; /* re-tuning is needed */
> int hold_retune; /* hold off re-tuning */
> unsigned int retune_period; /* re-tuning period in secs */
> struct timer_list retune_timer; /* for periodic re-tuning */
>
> need_retune is an integer so it can be set without needing
> synchronization. hold_retune is a integer to allow nesting.
>
> Various simple functions are provided to set / clear those
> variables.
>
> Subsequent patches take those functions into use.
>
> Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
> ---
> drivers/mmc/core/host.c | 68 ++++++++++++++++++++++++++++++++++++++++++++++++
> drivers/mmc/core/host.h | 6 +++++
> include/linux/mmc/host.h | 28 ++++++++++++++++++++
> 3 files changed, 102 insertions(+)
>
> diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
> index 8be0df7..e90e02f 100644
> --- a/drivers/mmc/core/host.c
> +++ b/drivers/mmc/core/host.c
> @@ -301,6 +301,73 @@ static inline void mmc_host_clk_sysfs_init(struct mmc_host *host)
>
> #endif
>
> +void mmc_retune_enable(struct mmc_host *host)
> +{
> + host->can_retune = 1;
> + if (host->retune_period)
> + mod_timer(&host->retune_timer,
> + jiffies + host->retune_period * HZ);
> +}
> +
> +void mmc_retune_disable(struct mmc_host *host)
> +{
> + host->can_retune = 0;
> + del_timer_sync(&host->retune_timer);
> + host->retune_now = 0;
> + host->need_retune = 0;
> +}
> +
> +void mmc_retune_timer_stop(struct mmc_host *host)
> +{
> + del_timer_sync(&host->retune_timer);
> +}
> +EXPORT_SYMBOL(mmc_retune_timer_stop);
> +
> +void mmc_retune_hold(struct mmc_host *host)
> +{
> + if (!host->hold_retune)
> + host->retune_now = 1;
> + host->hold_retune += 1;
> +}
> +
> +void mmc_retune_release(struct mmc_host *host)
> +{
> + if (host->hold_retune)
> + host->hold_retune -= 1;
> + else
> + WARN_ON(1);
> +}
> +
> +int mmc_retune(struct mmc_host *host)
> +{
> + int err;
> +
> + if (host->retune_now)
> + host->retune_now = 0;
> + else
> + return 0;
> +
> + if (!host->need_retune || host->doing_retune || !host->card)
> + return 0;
> +
> + host->need_retune = 0;
> +
> + host->doing_retune = 1;
> +
> + err = mmc_execute_tuning(host->card);
> +
> + host->doing_retune = 0;
> +
> + return err;
> +}
> +
> +static void mmc_retune_timer(unsigned long data)
> +{
> + struct mmc_host *host = (struct mmc_host *)data;
> +
> + mmc_retune_needed(host);
> +}
> +
> /**
> * mmc_of_parse() - parse host's device-tree node
> * @host: host whose node should be parsed.
> @@ -504,6 +571,7 @@ struct mmc_host *mmc_alloc_host(int extra, struct device *dev)
> #ifdef CONFIG_PM
> host->pm_notify.notifier_call = mmc_pm_notify;
> #endif
> + setup_timer(&host->retune_timer, mmc_retune_timer, (unsigned long)host);
>
> /*
> * By default, hosts do not support SGIO or large requests.
> diff --git a/drivers/mmc/core/host.h b/drivers/mmc/core/host.h
> index f2ab9e5..992bf53 100644
> --- a/drivers/mmc/core/host.h
> +++ b/drivers/mmc/core/host.h
> @@ -15,5 +15,11 @@
> int mmc_register_host_class(void);
> void mmc_unregister_host_class(void);
>
> +void mmc_retune_enable(struct mmc_host *host);
> +void mmc_retune_disable(struct mmc_host *host);
> +void mmc_retune_hold(struct mmc_host *host);
> +void mmc_retune_release(struct mmc_host *host);
> +int mmc_retune(struct mmc_host *host);
> +
> #endif
>
> diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
> index b5bedae..9c9e51b 100644
> --- a/include/linux/mmc/host.h
> +++ b/include/linux/mmc/host.h
> @@ -12,6 +12,7 @@
>
> #include <linux/leds.h>
> #include <linux/mutex.h>
> +#include <linux/timer.h>
> #include <linux/sched.h>
> #include <linux/device.h>
> #include <linux/fault-inject.h>
> @@ -321,10 +322,18 @@ struct mmc_host {
> #ifdef CONFIG_MMC_DEBUG
> unsigned int removed:1; /* host is being removed */
> #endif
> + unsigned int can_retune:1; /* re-tuning can be used */
> + unsigned int doing_retune:1; /* re-tuning in progress */
> + unsigned int retune_now:1; /* do re-tuning at next req */
>
> int rescan_disable; /* disable card detection */
> int rescan_entered; /* used with nonremovable devices */
>
> + int need_retune; /* re-tuning is needed */
> + int hold_retune; /* hold off re-tuning */
> + unsigned int retune_period; /* re-tuning period in secs */
> + struct timer_list retune_timer; /* for periodic re-tuning */
> +
> bool trigger_card_event; /* card_event necessary */
>
> struct mmc_card *card; /* device attached to this host */
> @@ -513,4 +522,23 @@ static inline bool mmc_card_hs400(struct mmc_card *card)
> return card->host->ios.timing == MMC_TIMING_MMC_HS400;
> }
>
> +void mmc_retune_timer_stop(struct mmc_host *host);
> +
> +static inline void mmc_retune_needed(struct mmc_host *host)
> +{
> + if (host->can_retune)
> + host->need_retune = 1;
> +}
> +
> +static inline void mmc_retune_not_needed(struct mmc_host *host)
> +{
> + host->need_retune = 0;
> +}

This function isn't required and has no users. Let's remove it.

> +
> +static inline void mmc_retune_recheck(struct mmc_host *host)
> +{
> + if (host->hold_retune <= 1)
> + host->retune_now = 1;
> +}
> +
> #endif /* LINUX_MMC_HOST_H */

Kind regards
Uffe